1. Field of the Invention
The present invention relates to a lens system suitable for an interchangeable lens for a single-lens reflex camera and a photocopy lens, and an optical apparatus equipped with the lens system.
2. Related Background Art
A so-called double-Gauss type lens system has been used as a lens system used for an interchangeable lens for a single-lens reflex camera and a photocopy lens, and a lot of lens systems have been proposed in such as Japanese Patent Application Laid-Open No. 2007-333790. Regarding such a double-Gauss type lens system, request for suppressing ghost images and flare, which deteriorate optical performance, as well as aberrations becomes increasingly strong. Accordingly, a higher optical performance is required to antireflection coatings applied to a lens surface, so that in order to meet such request, multilayer design technology and multilayer coating technology are continuously progressing (for example, see Japanese Patent Application Laid-Open No. 2000-356704).
However, a conventional double-Gauss type lens system generates large coma, so that it does not have sufficiently high optical performance. In addition, there is a problem that reflection light producing ghost images and flare is liable to be generated.